It is common to join workpieces, such as boards or, more generally, lumber or even metal or plastics, in a variety of configurations using dowels or pegs to ensure proper alignment of adjacent surfaces as well as to increase the strength of the joint being formed. Using examples and terminology most common to the wood craftsman, but without so limiting the use of the present invention, this technique of joining workpieces with the aid of dowels or pegs is often used to produce a wide board from a plurality of smaller width boards, or to produce mitered corner joints, or to produce plain corner joints, or to form T-shaped joints. This general technique may also be employed to produce adjustable shelves where each shelf is supported by a plurality of pegs inserted into corresponding sets of holes drilled into the faces of opposing vertical sides of a cabinet.
The common problem to be solved in all of the above cases is the precise positioning and/or alignment of adjoining holes required to produce flat boards, perpendicular joints or level shelves. A common method of matching the positions of holes is to measure and mark each location by hand. This method, however, is highly inaccurate because two measurements must be made to describe the location of each hole on each adjoining workpiece. Additionally, those skilled in the art know that measurement errors may be multiplied if the location of both of a set of matching holes are measured and marked incorrectly.
For this reason, a variety of fixtures have been developed which enable the craftsman to produce acceptable and repeatable results. These fixtures, however, are either complicated to use and/or expensive to manufacture or are structured in a rigid, non-adjustable fashion exhibiting diminished utility.
U.S. Pat. Nos. 4,145,160, 4,153,384 and 4,377,357 are representative of the more complicated fixtures previously developed. These fixtures are composed of several parts. Furthermore, use of these fixtures requires care and thought as complicated clamping schemes form a part of their structure. This also increases the time required to set up the fixtures. In addition, these fixtures are limited in their use, because of preset hole sizes and hole placement, i.e., the user can perform drilling applications on a limited number of sizes of articles and at a limited number of locations on a particular article.
U.S. Pat. Nos. 4,421,442 and 4,730,959 present fixtures which, although relatively easy to use, are limited in their application. These fixtures, practically speaking, may be used only for drilling holes into the edge of a board. Furthermore, the size hole is fixed as is the location or depth of the hole with respect to a face of the workpiece.
U.S. Pat. Nos. 2,798,520 and 4,893,970 are directed to drill fixtures which are uncomplicated but which are severely restricted in their use. Neither of these devices provides for use of different size drills nor is there any means for varying the depth at which the hole may be bored. Additionally, although these fixtures may be used to drill holes in the face of a board, the user must still rely on hand measurements to position the tool, unless the holes are to be drilled at the fixed depth from an edge of the board provided by the design of the tool. The disclosure of each of the above mentioned U.S. Patens are herein incorporated, in their entirety, by reference.